Semiconductor device and fabricating method thereof

ABSTRACT

A semiconductor device and a fabricating method thereof are provided. The semiconductor device includes a semiconductor structure and an input/output pad. The semiconductor structure includes a first substrate and a conductive layer, in which the first substrate has a first surface and a second surface opposite to each other, the conductive layer is disposed on the first surface of the first substrate, and the conductive layer includes one or more first trace. The first semiconductor structure has a recess penetrating the first substrate and exposing the one or more first trace, and the input/output pad is disposed on the one or more first trace and in the recess.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2019/103021 filed on 2019 Aug. 28, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a semiconductor device and afabricating method thereof.

2. Description of the Prior Art

Planar memory cells are scaled to smaller sizes by improving processtechnology, circuit design, programming algorithm, and fabricationprocess. However, as feature sizes of the memory cells approach a lowerlimit, planar process and fabrication techniques become challenging andcostly. As a result, memory density for planar memory cells approachesan upper limit.

A three-dimensional (3D) memory architecture can address the densitylimitation in planar memory cells. The 3D memory architecture includes amemory array and peripheral devices for controlling signals to and fromthe memory array device. Refer to FIG. 1 which illustrates aninput/output (I/O) pad structure of a conventional 3D memory device. Inthe I/O pad structure 10 of the conventional 3D memory device, thesubstrate 12 for forming memory array device 14 may be etched through toform through holes 12 h for electrically connecting the memory arraydevice 14 under the substrate 12 to the I/O pad 16 on the substrate 12.In order to form the I/O pad structure 10, an insulating layer 18 isfurther formed on a surface 12 a of the substrate 12 opposite to thememory array device 14, so that the I/O pad 16 formed on the insulatinglayer 18 can be insulated from the substrate 12 that has some elements,such as doped regions, formed therein. Also, the through holes 12 h isformed through the insulating layer 18 and the substrate 12, and athrough silicon contact (TSC) 20 and a liner layer 22 are formed in eachthrough hole 12 h, in which the liner layer 22 is located between theTSC 20 and the substrate 12 for electrically insulating them from eachother. The TSC 20 penetrates through the substrate 12 and electricallyconnects the I/O pad 16 to a through array contact 14 c of the memoryarray device 14 formed on another surface 12 b of the substrate 12opposite the surface 12 a. A passivation layer 24 is formed on the I/Opad 16 and has an opening 24 a exposing the I/O pad 16.

However, some shortcomings in the following description are stillpresent in the conventional I/O pad structure 10. First, a parasiticcapacitance generated between the I/O pad 16 and the substrate 12 willstrongly affect the operating speed of the 3D memory device or the speedfor storing or reading data in the 3D memory device, and thus, to reducethe affection, the thickness of the insulating layer 18 may be increasedto reduce the parasitic capacitance, but the parasitic capacitance alsoexists between the TSC 20 and the substrate 12. Second, when thethickness of the insulating layer 18 is increased, for example, to begreater than 1.4 microns, the aspect ratio of each through hole 12 hpenetrating through the insulating layer 18 and the substrate 12 isincreased, thereby significantly enlarging process difficulty. Third,because of the increased thickness of the insulating layer 18, moreadvanced technologies, such as machines for forming the through holes 12h with larger aspect ratios through the substrate 12, for fillingtungsten glue into the through holes 12 h with larger aspect ratios, fordepositing the liner layer 22 in the through holes 12 h with largeraspect ratios, and etc., are required. Thus, the cost of the 3D memorydevice cannot be further lowered. Third, with the advanced technology,the number of layers of a memory stack needs to be increased. In suchsituation, the space between two of the through array contacts 14 cbecomes smaller, such that the opening of each through hole 12 h will besmaller, and the space between the TSC 20 and the substrate 12 isreduced, thereby increasing the parasitic capacitance and slowing theoperating speed of the 3D memory device. For this reason, differenttechnology generations cannot continuously share the same architecture.Fourth, since the opening of each through hole 12 h is limited by thespace between two of the through array contacts 14 c, the opening ofeach through hole 12 h is small and limited, such that small deviationof through holes 12 h generated from the process error may result inopen circuit between the through array contact 14 c and the I/O pad 16or current leakage in the memory array device 14.

SUMMARY OF THE INVENTION

Embodiments of a semiconductor device and a fabricating method thereofare described in the present invention.

According to an embodiment of the present invention, a semiconductordevice is disclosed. The semiconductor device includes a firstsemiconductor structure and an input/output pad. The first semiconductorstructure includes a first substrate and a conductive layer, in whichthe first substrate has a first surface and a second surface opposite toeach other, the conductive layer is disposed on the first surface of thefirst substrate, and the conductive layer comprises one or more firsttrace. The input/output pad disposed on the one or more first trace. Thefirst semiconductor structure has a recess penetrating the firstsubstrate and exposing the one or more first trace, and the input/outputpad is disposed in the recess.

In some embodiments, the semiconductor device further includes a firstinsulating layer disposed on the second surface of the first substrate,and the first insulating layer has an opening corresponding to therecess.

In some embodiments, the first semiconductor structure further includesa second insulating layer between the first surface of the firstsubstrate and the first conductive layer, in which the recess penetratesthrough the second insulating layer.

In some embodiments, a thickness of the input/output pad may be lessthan a thickness of the second insulating layer

In some embodiments, the first semiconductor structure further includesa peripheral device on the first substrate.

In some embodiments, the conductive layer further includes at least twosecond traces electrically connected to the one or more peripheraldevice.

In some embodiments, the input/output pad directly contacts the one ormore first trace.

In some embodiments, a width of the one or more trace is greater than awidth of a bottom of the recess.

In some embodiments, the semiconductor device further includes a secondsemiconductor structure bonded to the first semiconductor structure.

In some embodiments, the second semiconductor structure includes asecond substrate and a plurality of NAND strings, and the NAND stringsare disposed between the conductive layer and the second substrate.

In some embodiments, the first semiconductor structure further includesone or more peripheral device on the first substrate, and one of NANDstrings is electrically connected to the one or more peripheral device.

According to an embodiment of the present invention, a fabricatingmethod of a semiconductor device is disclosed and includes providing atemporary semiconductor structure, wherein the temporary semiconductorstructure comprises a temporary substrate and a conductive layer, thetemporary substrate has a first surface, the conductive layer isdisposed on the first surface of the temporary substrate, and theconductive layer comprises one or more first trace; forming a recess inthe temporary semiconductor structure to form a first semiconductorstructure and a first substrate, wherein the recess penetrates throughthe first substrate and expose the one or more first trace; and forminga input/output pad in the recess and on the one or more first trace.

In some embodiments, the fabricating method further includes thinning asurface of the temporary substrate opposite to the first surface to forma second surface between providing the temporary semiconductor structureand forming the recess.

In some embodiments, the fabricating method further includes forming afirst insulating layer on the temporary substrate between providing thetemporary semiconductor structure and forming the recess, wherein thefirst insulating layer has an opening exposing the temporary substrate.

In some embodiments, the temporary semiconductor structure furthercomprises a temporary insulating layer between the first surface of thetemporary substrate and the conductive layer, and forming the recesscomprises patterning the temporary insulating layer to form a secondinsulating layer.

In some embodiments, forming the input/output pad includes depositing aconductive material layer on the first insulating layer, a sidewall ofthe recess, and the one or more first trace, and removing a part of theconductive material layer on the first insulating layer and a sidewallof the recess.

In some embodiments, the input/output pad is directly formed on the oneor more first trace.

In some embodiments, providing the first semiconductor structureincludes providing the temporary semiconductor structure comprisesproviding a second semiconductor structure bonded to the temporarysemiconductor structure.

Other aspects of the present disclosure can be understood by thoseskilled in the art in light of the description, the claims, and thedrawings of the present disclosure.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate embodiments of the present inventionand, together with the description, further serve to explain theprinciples of the present invention and to enable a person skilled inthe pertinent art to make and use the present invention.

FIG. 1 illustrates an input/output pad structure of a conventional 3Dmemory device.

FIG. 2 schematically illustrates a cross-sectional view of an exemplarysemiconductor device according to a first embodiment of the presentinvention.

FIG. 3 schematically illustrates a cross-sectional view of thesemiconductor device according to an example of the first embodiment ofthe present invention.

FIG. 4 is a flowchart of an exemplary fabricating method of thesemiconductor device according to the first embodiment of the presentinvention.

FIG. 5 to FIG. 8 schematically illustrate exemplary fabrication steps ofthe semiconductor device.

FIG. 9 schematically illustrates an exemplary semiconductor deviceaccording to a second embodiment of the present invention.

DETAILED DESCRIPTION

Although specific configurations and arrangements are discussed, itshould be understood that this is done for illustrative purposes only. Aperson skilled in the pertinent art will recognize that otherconfigurations and arrangements can be used without departing from thespirit and scope of the present invention. It will be apparent to aperson skilled in the pertinent art that the present invention can alsobe employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “some embodiments,” etc.,indicate that the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of aperson skilled in the pertinent art to effect such feature, structure orcharacteristic in connection with other embodiments whether or notexplicitly described.

In general, terminology may be understood at least in part from usage incontext. For example, the term “one or more” as used herein, dependingat least in part upon context, may be used to describe any feature,structure, or characteristic in a singular sense or may be used todescribe combinations of features, structures or characteristics in aplural sense. Similarly, terms, such as “a,” “an,” or “the,” again, maybe understood to convey a singular usage or to convey a plural usage,depending at least in part upon context.

It should be readily understood that the meaning of “on,” “above,” and“over” in the present invention should be interpreted in the broadestmanner such that “on” not only means “directly on” something but alsoincludes the meaning of “on” something with an intermediate feature or alayer therebetween, and that “above” or “over” not only means themeaning of “above” or “over” something but can also include the meaningit is “above” or “over” something with no intermediate feature or layertherebetween (i.e., directly on something).

The spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. The apparatus may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein may likewise be interpretedaccordingly.

As used throughout this application, the word “may” is used in apermissive sense (e.g., meaning having the potential to), rather thanthe mandatory sense (e.g., meaning must). The words “include”,“including”, and “includes” indicate open-ended relationships andtherefore mean including, but not limited to. Similarly, the words“have”, “having”, and “has” also indicated open-ended relationships, andthus mean having, but not limited to. The terms “first”, “second”,“third,” and so forth as used herein are meant as labels to distinguishamong different elements and may not necessarily have an ordinal meaningaccording to their numerical designation.

In the present invention, different technical features in differentembodiments described in the following description can be combined,replaced, or mixed with one another to constitute another embodiment.

Refer to FIG. 2 which schematically illustrates a cross-sectional viewof an exemplary semiconductor device according to a first embodiment ofthe present invention. As shown in FIG. 2, the semiconductor device 1provided in this embodiment includes a first semiconductor structure 102and an input/output (I/O) pad 104, in which the first semiconductorstructure 102 has a recess 102R for disposing the I/O pad 104 that iselectrically connected to external circuits or devices to transferelectrical signals between the semiconductor device 1 and the externalcircuits or devices. In FIG. 2, one I/O pad 104 is illustrated, but thenumber of the I/O pad 104 of the present invention is not limited tothis and may be plural. In this embodiment, the first semiconductorstructure 102 includes a first substrate 110 and one or more conductivelayer 112, in which the first substrate 110 has a first surface 110 aand the second surface 110 b opposite to each other, and the conductivelayer 112 is disposed on the first surface 110 a of the first substrate110. The conductive layer 112 may include one or more first trace 112T1exposed by the recess 102R, and the I/O pad 104 is disposed on andelectrically connected to the first trace 112T1. By means of disposingthe I/O pad 104 in the recess 102R, the parasitic capacitance generatedbetween the I/O pad 104 and the first substrate 110 can be reduced. Thefirst semiconductor structure 102 may for example be a peripheral devicestructure, so the first semiconductor structure 102 may include thefirst substrate 110 and a peripheral interconnect layer 108 on the firstsurface 110 a of the first substrate 110, and the conductive layer 112is included in the peripheral interconnect layer 108. The firstsemiconductor structure 102 may further include a peripheral device 106on the first surface 110 a of the first substrate 110 and between theperipheral interconnect layer 108 and the first substrate 110. The firstsubstrate 110 for example can include silicon (e.g., single crystallinesilicon), silicon germanium (SiGe), gallium arsenide (GaAs), germanium(Ge), silicon on insulator (SOI), or any other suitable materials. Theconductive layer 112 may for example include conductor materialsincluding, but not limited to, W, Co, Cu, Al, silicides, or anycombination thereof.

It is noted that X and Y axes are added in FIG. 2 to further illustratethe spatial relationship of the components in semiconductor device 1.The first substrate 110 includes two lateral surfaces (e.g., the firstsurface 110 a and the second surface 110 b) extending laterally in adirection X (the lateral direction or width direction). As used herein,one component (e.g., a layer or a device) is “on”, “above”, or “under”another component (e.g., a layer or a device) of the semiconductordevice is determined relative to the substrate of the semiconductordevice (e.g., the first substrate 110) in another direction Y (thevertical direction or thickness direction). The same notion fordescribing spatial relationship is applied throughout the presentdisclosure.

In this embodiment, the first substrate 110 may have a device region DRand a pad region PR. The device region DR is for forming the peripheraldevice 106, and the pad region PR is for forming the recess 102R and theI/O pad 104, such that the peripheral device 106 is not affected ordamaged by the formation of the recess 102R and the I/O pad 104. Thus,the first substrate 110 can be etched through to have an opening 110Pcorresponding to the recess 102R.

The peripheral device 106 may include one or more transistor. In theembodiment shown in FIG. 2, one transistor is illustrated as an example,but not limited thereto. The peripheral device 106 may for exampleinclude doped regions 106 a and a gate structure 106 b. The dopedregions 106 a are disposed in the first substrate 110. The gatestructure 106 b may be disposed between the first substrate 110 and theperipheral interconnect layer 108.

The peripheral interconnect layer 108 includes the conductive layer 112and one or more insulating layer, such that the peripheral device 106may be electrically connected to the I/O pad 104 or other devices, suchas following memory array device. In the embodiment shown in FIG. 2, oneconductive layer 112 and two insulating layers 114 a, 114 b areillustrated as an example, but not limited thereto. Each of theinsulating layers 114 a, 114 b can include dielectric materials, such assilicon oxide, silicon nitride, silicon oxynitride, any other suitabledielectric materials, or any combination thereof. The conductive layer112 is disposed on the first surface 110 a of the first substrate 110and between the insulating layers 114 a, 114 b, and the insulating layer114 a is disposed between the conductive layer 112 and the firstsubstrate 110, such that some parts of the conductive layer 112 may beelectrically isolated from the first substrate 110 by the insulatinglayer 114 a.

In this embodiment, the recess 102R further penetrates the insulatinglayer 114 a between the first substrate 110 and the conductive layer 112and exposes the first trace 112T1, such that the insulating layer 114 ahas an opening 114P corresponding to the recess 102R. For example, theopening 110P, the opening 114P, the exposed first trace 112T1 and a partof the insulating layer 114 b may form the recess 102R.

Furthermore, the semiconductor device 1 may further include anotherinsulating layer 118 disposed on the second surface 110 b of the firstsubstrate 110, in which the insulating layer 118 has an opening 118Pcorresponding to the recess 102R. In other words, the opening 118Pexposes the recess 102R. Thus, the I/O pad 104 can be formed on theconductive layer 112 through the opening 118P and the recess 102R andelectrically connected to the exposed first trace 112T1 by beingdisposed in the recess 102R. For example, the I/O pad 104 can directlycontact the first trace 112T1. In the embodiment shown in FIG. 2, thenumber of the exposed first traces 112T1 spaced apart from each other isplural, and the I/O pad 104 is electrically connected to the pluralfirst traces 112T1, but not limited thereto. In some embodiments, thenumber of the exposed first trace 112T1 may be one, and a width of thefirst trace 112T1 may be the same as or different from a width of abottom of the recess 102R. Preferably, the width of the first trace112T1 may be greater than the width of the bottom of the recess 102R, sothe first trace 112T1 may serve as an etching stop layer while formingthe recess 102R. In some embodiments, the conductive layer 112 may beone of the conductive layers in the peripheral interconnect layer 108closest to the first substrate 110, but not limited thereto. In someembodiments, the conductive layer 112 may further include at least twosecond traces 112T2 electrically connected to the peripheral device 106.In some embodiments, the number of the insulating layers penetrated bythe recess 102R may be plural. In some embodiments, the thickness T1 ofthe conductive layer 112 may be less than the thickness T2 of theinsulating layer 114 a, such that the space between the conductive layer112 and the first substrate 110 can be increased to lower the parasiticcapacitance between them.

In some embodiments, the peripheral interconnect layer 108 may furtherinclude at least one contact layer 116 for electrically connecting theperipheral device 106 to the conductive layer 112. For example, thecontact layer 116 includes contact plugs penetrate through theinsulating layer 114 a. In some embodiments, the peripheral interconnectlayer 108 may further include contact layer under the conductive layer112, but not limited thereto. The conductive layer 116 may for exampleinclude conductor materials including, but not limited to, W, Co, Cu,Al, silicides, or any combination thereof.

In some embodiments, the semiconductor device 1 may further include apassivation layer 120 for protecting the insulating layer 118, the firstsemiconductor structure 102 and the I/O pad 104. The passivation layer120 has an opening 120P exposing the I/O pad 104, so that the I/O pad104 can be electrically connected to external circuits or devicesthrough the opening 120P.

The semiconductor device may for example be a memory device or any othersuitable device. Refer to FIG. 3 which schematically illustrates across-sectional view of the semiconductor device according to an exampleof the first embodiment of the present invention. As shown in FIG. 3,the semiconductor device 1 provided in this example is a NAND Flashmemory device, but not limited thereto. The memory cells in the NANDFlash memory device are provided in the form of a plurality of NANDstrings 222 extending vertically under the first substrate 110. In thisexample, the semiconductor device 1 may further include a secondsemiconductor structure 224, and the second semiconductor structure 224includes a second substrate 226 and a memory array device 228. Thesecond substrate 226 is disposed opposite to the first surface 110 a ofthe first substrate 110, and the memory array device 228 is formed onthe second substrate 226 and between the first substrate 110 and thesecond substrate 226. The second substrate 226 for example can includesilicon (e.g., single crystalline silicon), silicon germanium (SiGe),gallium arsenide (GaAs), germanium (Ge), silicon on insulator (SOI), orany other suitable materials.

The memory array device 228 can include the NAND strings 222 disposedbetween the conductive layer 112 and the second substrate 226. The NANDstrings 222 extend vertically through a plurality of conductor layers230 and a plurality of dielectric layers 232. Each conductor layer 230and a corresponding one of the dielectric layers 232 may form a pair.Each conductor layer 230 can be adjoined by two dielectric layers 232 onboth sides, and each dielectric layer 232 can be adjoined by twoconductor layers 230 on both sides. Conductor layer 230 can includeconductor materials, such as tungsten (W), cobalt (Co), copper (Cu),aluminum (Al), doped silicon, silicides, any other suitable conductormaterials, or any combination thereof. Dielectric layer 232 can includedielectric materials, such as silicon oxide, silicon nitride, siliconoxynitride, any other suitable dielectric materials, or any combinationthereof. Also, the memory array device 228 may further include a sourcecontact 234, word line contacts 236, and a dielectric layer 238, inwhich the source contact 234 extends vertically through the conductorlayers 230 and the dielectric layers 232, the word line contacts 236extend vertically within the dielectric layer 238, and each word linecontact 236 is in contact with a corresponding conductor layer 230 toindividually address a corresponding word line of the memory arraydevice 228. It is noted that the memory array device 228 shown in FIG. 2is for an example, and the person skilled in the art knows the memoryarray device 228 may have other structures, so the structure or itsvariant of the memory array device 228 will not be detailed herein. Insome embodiments, an isolation region 240 and a doped region 242 may beformed in the second substrate 226.

As shown in FIG. 2, the semiconductor device 1 may further include anarray interconnect layer 244 for electrically connecting the memoryarray device 228 to the peripheral device 106 and/or the I/O pad 104.For example, one of NAND strings 222 is electrically connected to theperipheral device 106 through the array interconnect layer 244 and theperipheral interconnect layer 108. The array interconnect layer 244 isdisposed on the memory array device 228 and in contact with theperipheral interconnect layer 108. The array interconnect layer 244 caninclude one or more contact layer (e.g. contact layers 246 a, 246 b),one or more conductive layer (e.g. conductive layers 248 a, 248 b), andone or more dielectric layer (e.g. dielectric layers 250 a, 250 b). Thecontact layers 246 a, 246 b and the conductive layers 248 a, 248 b mayinclude conductor materials including, but not limited to, W, Co, Cu,Al, silicides, or any combination thereof. The dielectric layers 250 a,250 b may include dielectric materials including, but not limited to,silicon oxide, silicon nitride, low-k dielectrics, or any combinationthereof.

In this example, the peripheral interconnect layer 108 may includeplural conductive layers 112 (e.g. conductive layers 112 a, 112 b),plural contact layers 116 (e.g. contact layers 116 a, 116 b), and pluraldielectric layers (e.g. dielectric layers 114 a, 114 b, 114 c). In someembodiments, the number of the contact layer 116 and the number of thedielectric layer are not limited to be plural and may be adjusted basedon the number of the conductive layer 112. A bonding interface 252 maybe formed between the dielectric layer 114 c of the peripheralinterconnect layer 108 and the dielectric layer 250 a of the arrayinterconnect layer 244. The bonding interface 252 may also be formedbetween the conductor layer 248 a of the array interconnect layer 244and the conductor layer 112 b of the peripheral interconnect layer 108.In other words, the first semiconductor structure 102 is bonded to thesecond semiconductor structure 224 at the bonding interface 252. In someembodiments, the first semiconductor structure 102 may further includeisolation regions 154 formed in the first substrate 110 for separatingdifferent components.

As mentioned above, the semiconductor device 1 may have the followingadvantages as compared with the conventional memory device shown inFIG. 1. First, since the I/O pad 104 is directly disposed in the recess102R, the I/O pad 104 doesn't exist in the opening 110P of the firstsubstrate 110. Thus, the parasitic capacitance generated between the I/Opad 104 and the first substrate 110 can be reduced, thereby improvingthe operating speed of the semiconductor device 1 or the speed forstoring or reading data in the semiconductor device 1. Second, thethickness of the insulating layer 118 is not required to be increased toreduce the parasitic capacitance, such that the cost for forming theinsulating layer 118 can be lowered, and high aspect ratio is notrequired. Thus, the formation of the I/O pad 104 is not limited by thehigh aspect ratio of the through hole penetrating the insulating layerand the substrate, and the process difficulty for forming the I/O pad104 can be easier when the density of the NAND strings 22 is increased.Third, because the recess 102R is formed on the first semiconductorstructure 108 including the peripheral device 106, the width of therecess 102R (e.g. in a range from 70 μm to 80 μm) is not limited to besimilar to or the same as the width of the NAND string 222 or TSC,exposure light used in a photolithography process is not limited to havevery small wavelength. For example, the photolithographic process forforming the recess 102R may use I-line exposure (e.g. 365 nm). Sincethat, open circuit between the through array contact and the I/O pad orcurrent leakage in the semiconductor device due to the process errorwill not occur. For this reason, more advanced technologies, such asmachines for forming the through holes with larger aspect ratios throughthe substrate, for filling tungsten glue into the through holes withlarger aspect ratios, for depositing the liner layer in the throughholes with larger aspect ratios, and etc., are not required. Fourth,when the number of conductor layers 230 and the dielectric layers 232are increased to upgrade memory capacity, different technologygenerations still can easily share the same semiconductor device 1.

FIG. 4 is a flowchart of an exemplary fabricating method of thesemiconductor device according to the first embodiment of the presentinvention. FIG. 5 to FIG. 8 and FIG. 2 schematically illustrateexemplary fabrication steps of the semiconductor device, in which forclarity, FIG. 6 to FIG. 8 ignore a part of the first semiconductorstructure and the second semiconductor structure, but the presentinvention is not limited thereto. It should be noted that the stepsshown in FIG. 4 are not exhaustive and that other steps may be performedas well before, after, or between any of the illustrated steps. Thefabricating method of the semiconductor device 1 provided in thisembodiment includes the following steps S12-S20. As shown in FIG. 4 andFIG. 5, the step S12 is performed to provide a temporary semiconductorstructure 302. The temporary semiconductor structure 302 includes atemporary substrate 310, a temporary insulating layer 314 a and one ormore conductive layer 112. The temporary semiconductor structure 302 isdifferent from the first semiconductor structure 102 in that thetemporary substrate 310 of the semiconductor structure 302 is notthinned and etched through in step S12, so the temporary semiconductorstructure 302 doesn't have the recess 102R, and the temporary substrate310 doesn't have the opening 110P. In some embodiments, the thickness ofthe temporary substrate 310 may be greater than that of the firstsubstrate 110 in step S12. In this embodiment, the temporary substrate310 has a first surface 110 a and a third surface 310 b opposite to eachother, the temporary peripheral interconnect layer 308 and theperipheral device 106 are formed on the first surface 110 a of thetemporary substrate 310. In step S12, the temporary peripheralinterconnect layer 308 is different from the peripheral interconnectlayer 108 mentioned above in that the temporary insulating layer 314 ais not etched through, so as not to have the opening 114P. In thisembodiment, the peripheral device 106 is similar to or the same as thementioned above and will not be detailed redundantly.

In step S12, the second semiconductor structure 224 is also provided andbonded to the temporary semiconductor structure 302. Since the secondsemiconductor structure 224 is the same as the mentioned above, thesecond semiconductor structure 224 will not be detailed repeatedly.

As shown in FIG. 4, FIG. 5 and FIG. 6, the step S14 is optionallyperformed to thin the third surface 310 b of the temporary substrate 310to form a second surface 110 b. For example, thinning the firstsubstrate 310 may include performing a chemical mechanical planarization(CMP) process or any other suitable process.

After thinning the temporary substrate 310, the step S16 is performed toform an insulating layer 118 on the second surface 110 b of the thinnedtemporary substrate 310, in which the insulating layer 118 has theopening 118P exposing the second surface 110 b of the temporarysubstrate 310. For example, forming the insulating layer 118 may includedepositing an insulating material layer and patterning the insulatingmaterial layer. The deposition of the insulating material layer may forexample utilize a chemical vapor deposition (CVD) process, a physicalvapor deposition (PVD) process, an atomic layer deposition (ALD) processor any other suitable deposition process. The patterning of theinsulating material layer may for example utilize a photolithographicprocess using a photomask (such as I-line mask). In some embodiments,the step S16 may be performed directly after providing the temporarysemiconductor structure 302.

After forming the insulating layer 118, the step S18 is performed toforming the recess 102R in the pad region PR of the temporarysemiconductor structure 302. Specifically, forming the recess 102R mayinclude patterning the exposed temporary substrate 310 to form theopening 110P in the temporary substrate 310, thereby forming theaforementioned first substrate 110 with the opening 110P. The patterningof the temporary substrate 310 may for example utilize an etchingprocess using the insulating layer 118 as a mask. Forming the recess102R may further include patterning a part of the temporary insulatinglayer 314 a exposed by the opening 110P to form the opening 114P andexpose the first traces 112T1 after forming the opening 110P, therebyforming the aforementioned insulating layer 114 a with the opening 114P.Accordingly, the first semiconductor structure 102 mentioned above canbe formed, and the peripheral interconnect layer 108 mentioned above canbe formed. The patterning of the temporary insulating layer 314 a mayfor example utilize an etching process selectively etching the temporaryinsulating layer 314 a relative to the insulating layer 118, the firstsubstrate 110 and the conductive layer 112. In some embodiments, theperipheral interconnect layer 308 may further include an etching stoplayer between the conductive layer 112 and the temporary insulatinglayer 314 a, so that the etching of the temporary insulating layer 314 acan be stopped at the etching stop layer, and the insulating layer 114 bbetween the first traces 112T1 can be protected. In some embodiment, theetching process may have high etching selectivity of the temporaryinsulating layer 314 a relative to the insulating layer 114 b.

As shown in FIG. 4 and FIG. 8, the step S20 is performed to form an I/Opad 104 in the recess 102R and on the first trace 112T1. Specifically,as shown in FIG. 7, forming the I/O pad 104 includes depositing aconductive material layer 104 m on the insulating layer 118, a sidewallof the recess 102R, and the first trace 112T1. In other words, theconductive material layer 104 m extend from the top surface of theinsulating layer 118 onto sidewalls of the opening 118P, sidewalls ofthe opening 110P, sidewalls of the opening 114P and the I/O pad 104. Thedeposition of the conductive material layer 104 m may use the CVDprocess, the PVD process, the ALD process or any other suitabledeposition process. Subsequently, as shown in FIG. 8, forming the I/Opad 104 further includes patterning the conductive material layer 104 mto remove parts of the conductive material layer 104 m on the insulatinglayer 118 and sidewalls of the recess 102R.

As shown in FIG. 2, after the I/O pad 104 is formed, a passivation layer120 may be further formed on the insulating layer 118, sidewalls of theopening 110P, sidewalls of the opening 114P and the I/O pad 104, andthen, the passivation layer 120 is patterned to have an opening 120Pexposing the I/O pad 104. Accordingly, the semiconductor device 1 ofthis embodiment is formed.

The following description will detail the different embodiments of thepresent disclosure. To simplify the description, identical components ineach of the following embodiments are marked with identical symbols. Formaking it easier to understand the differences between the embodiments,the following description will detail the dissimilarities amongdifferent embodiments and the identical features will not be redundantlydescribed.

Refer to FIG. 9 which schematically illustrates an exemplarysemiconductor device according to a second embodiment of the presentinvention. As shown in FIG. 9, the semiconductor device 2 provided inthis embodiment is different from the previous embodiment in that awidth W1 of the first trace 112T1 may be the greater a width W2 of abottom of the recess 102R, so the first trace 112T1 may serve as anetching stop layer while forming the recess 102R.

By using the disclosed semiconductor device and fabricating methodthereof, the parasitic capacitance generated between the I/O pad and thefirst substrate can be reduced, thereby improving the operating speed ofthe memory device or the speed for storing or reading data in the memorydevice. Also, the thickness of the insulating layer on the firstsubstrate is not required to be increased to reduce the parasiticcapacitance, such that the cost for forming the insulating layer can belowered, and high aspect ratio is not required. Thus, the formation ofthe I/O pad is not limited by the high aspect ratio, and the processdifficulty for forming the I/O pad can be easier when the density of theNAND strings is increased. Because the recess is formed on the firstsemiconductor structure including the peripheral device, the width ofthe recess of the first semiconductor structure is not limited to besimilar to or the same as the width of the NAND string or TSC, exposurelight used in the photolithography process can have larger wavelength.Also, open circuit between the through array contact and the I/O pad orcurrent leakage in the semiconductor device due to the process errorwill not occur, and more advanced technologies are not required.Furthermore, when the number of conductor layers and the dielectriclayers are increased to upgrade memory capacity, different technologygenerations still can easily use the same architecture.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the present invention that others can, byapplying knowledge within the skill of the art, readily modify and/oradapt, for various applications, such specific embodiments, withoutundue experimentation, and without departing from the general concept ofthe present invention. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the invention and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the invention andguidance.

Embodiments of the present invention have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The Summary and Abstract sections can set forth one or more but not allexemplary embodiments of the present invention as contemplated by theinventor(s), and thus, are not intended to limit the present inventionand the appended claims in any way.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A semiconductor device, comprising: a firstsemiconductor structure, comprising a first substrate and a conductivelayer, wherein the first substrate has a first surface and a secondsurface opposite to each other, the conductive layer is disposed on thefirst surface of the first substrate, and the conductive layer comprisesone or more first trace; and an input/output pad disposed on the one ormore first trace; wherein the first semiconductor structure has a recesspenetrating the first substrate and exposing the one or more firsttrace, and the input/output pad is disposed in the recess.
 2. Thesemiconductor device according to claim 1, further comprising a firstinsulating layer disposed on the second surface of the first substrate,wherein the first insulating layer has an opening corresponding to therecess.
 3. The semiconductor device according to claim 1, wherein thefirst semiconductor structure further comprises a second insulatinglayer between the first surface of the first substrate and the firstconductive layer, wherein the recess penetrates through the secondinsulating layer.
 4. The semiconductor device according to claim 3,wherein a thickness of the input/output pad is less than a thickness ofthe second insulating layer.
 5. The semiconductor device according toclaim 1, wherein the first semiconductor structure further comprises aperipheral device on the first substrate.
 6. The semiconductor deviceaccording to claim 5, wherein the conductive layer further comprises atleast two second traces electrically connected to the peripheral device.7. The semiconductor device according to claim 1, wherein theinput/output pad directly contacts the one or more first trace.
 8. Thesemiconductor device according to claim 1, wherein a width of the one ormore trace is greater than a width of a bottom of the recess.
 9. Thesemiconductor device according to claim 1, further comprising a secondsemiconductor structure bonded to the first semiconductor structure. 10.The semiconductor device according to claim 9, wherein the secondsemiconductor structure comprises a second substrate and a plurality ofNAND strings, and the NAND strings are disposed between the conductivelayer and the second substrate.
 11. The semiconductor device accordingto claim 10, wherein the first semiconductor structure further comprisesa peripheral device on the first substrate, and one of NAND strings iselectrically connected to the peripheral device.
 12. A fabricatingmethod of a semiconductor device, comprising: providing a temporarysemiconductor structure, wherein the temporary semiconductor structurecomprises a temporary substrate and a conductive layer, the temporarysubstrate has a first surface, the conductive layer is disposed on thefirst surface of the temporary substrate, and the conductive layercomprises one or more first trace; forming a recess in the temporarysemiconductor structure to form a first semiconductor structure and afirst substrate, wherein the recess penetrates through the firstsubstrate and expose the one or more first trace; and forming aninput/output pad in the recess and on the one or more first trace. 13.The fabricating method of the semiconductor device according to claim12, further comprising thinning a surface of the temporary substrateopposite to the first surface to form a second surface between providingthe temporary semiconductor structure and forming the recess.
 14. Thefabricating method of the semiconductor device according to claim 12,further comprising forming a first insulating layer on the temporarysubstrate between providing the temporary semiconductor structure andforming the recess, wherein the first insulating layer has an openingexposing the temporary substrate.
 15. The fabricating method of thesemiconductor device according to claim 14, wherein the temporarysemiconductor structure further comprises a temporary insulating layerbetween the first surface of the temporary substrate and the conductivelayer, and forming the recess comprises patterning the temporaryinsulating layer to form a second insulating layer.
 16. The fabricatingmethod of the semiconductor device according to claim 15, wherein athickness of the input/output pad is less than a thickness of the secondinsulating layer.
 17. The fabricating method of the semiconductor deviceaccording to claim 14, wherein forming the input/output pad comprises:depositing a conductive material layer on the first insulating layer, asidewall of the recess, and the one or more first trace; and removing apart of the conductive material layer on the first insulating layer anda sidewall of the recess.
 18. The fabricating method of thesemiconductor device according to claim 17, wherein the input/output padis directly formed on the one or more first trace.
 19. The fabricatingmethod of the semiconductor device according to claim 12, whereinproviding the temporary semiconductor structure comprises providing asecond semiconductor structure bonded to the temporary semiconductorstructure.
 20. The fabricating method of the semiconductor deviceaccording to claim 19, wherein the second semiconductor structurecomprises a second substrate and a plurality of NAND strings, and theNAND strings are disposed between the conductive layer and the secondsubstrate.